In a typical known scroll compressor, a pressing force toward a fixed scroll is applied to an orbiting scroll so as to prevent the orbiting scroll from moving away from the fixed scroll.
Japanese Unexamined Patent Publication No. 2001-214872 describes a scroll compressor in which high-pressure oil is supplied to the back surface of an orbiting scroll so that a pressing force toward a fixed scroll is applied to the orbiting scroll. This scroll compressor includes a seal ring that divides a back-pressure space at the back surface of the orbiting scroll into an inner first back-pressure space and an outer second back-pressure space. In the scroll compressor, high-pressure oil is supplied to the first back-pressure space, whereas the second back-pressure space serves as a low-pressure space, so that a pressing force is generated by a high-pressure force of the first back-pressure space.
In the scroll compressor, high-pressure oil is supplied to an oil groove formed in a thrust sliding surface between the fixed scroll and the orbiting scroll so that the pressing force is suppressed by a pushback force so as to prevent excessive pressing. The high-pressure oil supplied to the oil groove is distributed over the thrust sliding surface to be used for sealing as well as to lubricate the thrust sliding surface.
Japanese Unexamined Patent Publication No. 2010-043641 describes a scroll compressor including a communication passage that communicates a compression chamber and a back-pressure space in an end plate of an orbiting scroll. In the scroll pressure, refrigerant gas that is being compressed is introduced into the back-pressure space at the back surface of the orbiting scroll. In this scroll compressor, a pressure (i.e., an intermediate pressure) of refrigerant gas that is being compressed is caused to act on the back surface of the orbiting scroll, thereby pressing the orbiting scroll against the fixed scroll.